Improvement in locks



UNITED STATES LEWIS Gr. HOFFMAN, OF ALBANY, NEW YORK.

IMPROVEMENT IN LOCKS.

Specification forming part of Letters Patent No. 54,162, dated VApril 24, 1866.

To'all whom t may concern:

Beit known that I, LEWIS G. HOFFMAN, of the city of Albany, State of New York, have invented a new and useful Improvement in the Construction of Door-Locks and I declare the following specification, with the drawings forming part thereof', to be a full and complete description of my invention.

The 'object of my invention is to secure a door locked within from being opened by burglars by the use of false keys when its proper key has been withdrawn or by the turning ot' the key from the outside by the applica-tion ot' pinchers to the outer end ofits stem.

Figure l shows the interior of an ordinary door-lock with myimprovement attached g Fig. 2, an end view of the same.

Similar letters denote the same parts of the apparatus.

A is the bolt, which is moved to the right and left in the usual manner by its key. It is represented as projecting or locked within its Staple.

To the back end of the bolt at B, and parallel with its line of motion, I attach, by screwing it in or otherwise, a stout metal rod, C, (Wire,) extending from it through an orifice, D, perforated through the end wall of the lock, to the outer edge of that wall when the bolt is shot out, as shown.

To the outside of the wall I secure, byastrong screw or rivet, E, a stout button, Gr, so that when it is turned down, as shown in Fig.,1, over against the end of rod (l it cannot be forced outward; but when turned up or from over oriee D the rod can pass outward, permitting the bolt to be turned inward, the rod projecting through D.

By the useof this simple apparatus all attempts to open the lock from without when locked from Within, whether the key be left in the lock or not, Will be frustrated.

An important feature of my apparatus is that it can be applied at a trifling cost to all, or nearly all, of that class of door-locks that are not Inortise-looks, and therefore would be ot great benefit by being attached to the present locks of chambers ot' hotels, boarding-houses, or steamboats.

What I claim as my invention, and desire to secure by Letters Patent, is-

lhe rod O, oritice D, and the button E, as applied to door-locks, substantially as described and for the purposes set forth in the above specification.

LEWIS Gr. HOFFMAN.

Witnesses:

RICH. VARIOK DE WITT, A. V. DE WITT. 

